5 things to know about NASA’s Pluto flyby

NASA’s New Horizons spacecraft will make the first close-encounter pass to Pluto Tuesday morning after nine years and three billion miles traveled. Here is what you need to know about the fastest spacecraft ever launched and what it is out to discover about the former planet:

This July 11, 2015, image provided by NASA shows Pluto from the New Horizons spacecraft. On Tuesday, July 14, NASA’s New Horizons spacecraft will come closest to Pluto. New Horizons has traveled 3 billion miles over 9½ years to get to the historic point. (NASA/JHUAPL/SWRI via AP)

• In exploring Pluto, reclassified back in 2006 as a dwarf planet, scientists hope to explore “a whole new class of small planet.” Objects like Pluto that are part of the Kuiper Belt are thought to be some of the oldest bodies in the solar system.

• Since control messages from Earth take up to 4.5 hours to reach New Horizons as it nears Pluto, the spacecraft will be largely on its own as it makes its long-awaited, close-encounter pass. With speeds up 36,450 miles per hour, the piano-sized probe is also the world’s fastest.

• The ashes of Clyde Tombaugh, the farmer turned astronaut who originally discovered Pluto back in 1930, are aboard the spacecraft. VBSDC (Venetia Burney Student Dust Counter), an instrument named after the 11-year-old girl who named the planet, is also aboard.

New Horizons is on track to pass about 7,750 miles from Pluto at 7:49 am Eastern Daylight Time Tuesday. You can use NASA’s “Eyes on Pluto” app to follow along.